Well, we've been working on that for some time. We're going to limit how much people can progress through the minigames before they get cut off. Many social media games employ a similar tact, where they cut their players off after 15 minutes or so each day. In most cases, that is when they give their players an opportunity to advance by 'gifting' or 'sharing' virtual goods with their social networks - free marketing for the app, but obnoxious to the recipients of this spam.
In our case, we're going to have people cut off after so much time (or at least stop their advancement to more difficult virtual challenges) unless they go outside and actually do something in real life. As simple as checking in at a park or farmers market, maybe taking a picture of a flower, or their nursery, or an interesting fruit. Then, they have the option to share the picture or check-in with their friends and family, and instead of just spamming them with worthless game invites, they're actually showing them something they did in real life.
We're hoping that overcomes the 'invite fatigue' many people experience. We're also tying our currency to the number of 'likes' that our players get (controlling for bots and gaming the system), so they're encouraged to do things that their friends and family are actually proud of.
We'll see how it works, we're still working on the back end right now, getting all the databases and APIs to play nice with each other. We're still taking on investors and contributors.